The present invention relates to fluidically coupling fluidic components, in particular in a high performance liquid chromatography application.
In liquid chromatography, a fluidic sample (mobile phase) may be pumped through conduits and a column comprising a material (stationary phase) which is capable of separating different components of the fluidic analyte. Such a material, so-called beads which may comprise silica gel, may be filled into a column tube which may be connected to other elements (like a sampling unit, a flow cell, containers including sample and/or buffers) by conduits.
The flow path of the mobile phase typically comprises plural individual components coupled together, which, in turn, might also be comprised of individual sub-components. Due to the high pressure applied in most HPLC applications, pressure sealing of the components in and along the flow path is required. Sealings should also provide for a small dead volume and low carryover.
A so called fitting is a fluidic component being capable of providing a sealed connection between a capillary and another fluidic conduit (such as another capillary or a channel in a substrate or the like).
U.S. Pat. No. 6,494,500 discloses a universal self-adjusting high pressure liquid connector for use with high pressure liquid chromatography (HPLC) columns requiring liquid-tight and leak free seals between fittings and unions. The apparatus provides a liquid-tight seal between the end of a HPLC end fitting and a end cap thereby eliminating any potential dead volume in the area of the connection. The apparatus comprises a body, a fixed ferrule, a replaceable ferrule, a stem disposed in the body and a biasing spring slidingly mounted on a capillary tube of that extends through the connector. The spring biases the capillary tube of the connector into the HPLC end fitting, self-adjusting and maintaining a pressure sufficient to ensure a liquid-tight seal notwithstanding the depth of the HPLC tube stop or ferrule stop of the mating HPLC column.
However, the requirements regarding sealing performance and mechanical stability of a fluidic component of fluidic measurement devices increases with further increasing operation pressure values. At the same time, fast and easy handling of such a fitting by a user is required. With the advent of planar structures with integrated fluid channels, connection technology faces new challenges.
U.S. Pat. No. 5,988,703 discloses a fluid connector system for connecting a conduit having a fluid-bearing capability to a channel having a fluid-bearing capability in a planar manifold assembly, thereby providing a substantially leak-free fluid communication between the conduit and the channel. An embodiment of the fluid connector system is effective for connecting a conduit to a planar manifold situated in a sample analysis system. The conduit is located in a fluid-handling functional device and communicates with a device port located in a port surface region on the fluid handling functional device. Located within the port surface region, and encircling the first port, is a weld projection. The channel is located in a receiver portion of a planar assembly and communicates with a manifold port. A port surface region on the exterior of the planar assembly encompasses the manifold port. The port surface regions are complementary in that they may be superimposed so as to co-locate the device port and the manifold port. The leading edge may contact the port surface region on the planar manifold in a fashion that defines a line of contact. The weld projection and the material that underlies the line of contact are both formed of electrically resistive material suited to melting and subsequent fusion via resistive heating due to a brief application of an electric current. Accordingly, upon application of a current pulse that is sufficient to cause resistive heating at the weld projection, the weld projection and the material that underlies the line of contact are heated and intermixed, thereby becoming fused together. Upon cooling, the weld projection and the line of contact are merged and thus nearly indistinguishable, thus fixing the port surface regions together such that a hermetic seal is imposed about the juncture of the superimposed device port and manifold port.
US 2010/239462 discloses an assembly comprising at least one microfluidic device and a mounting piece, this microfluidic device comprising at least one material layer and at least one first fluidic port, which first fluidic port it situated at least partially in an end surface of the material layer and which mounting piece comprises at least one fluidic component, wherein the mounting piece is coupled to the microfluidic device by means of first coupling means provided for this purpose such that the fluidic component is connected to the first fluidic port.
However, the connection of planar structures having integrated fluid channels to an environment is still difficult.